1. Field of the Invention
The present invention relates generally to hair trimmers and more particularly to such trimmers which cut hair in the vicinity of the nostrils and ears with a rotating blade.
2. Description of the Related Art
Indicated generally at 10 in FIGS. 1-4 is a prior art trimmer for cutting nose and ear hairs. The main structural components include a generally cylindrical outer handle 12 and a generally cylindrical inner handle 14. A generally tubular outer blade 16 is received in one end of an axial bore 18 formed in outer handle 12. Received in outer blade 16 is a generally tubular inner blade 20. Cap 22 covers an upper end of outer handle 12. Gripping surfaces 24, 26 are formed on outer handle 12 and inner handle 14, respectively.
Before describing in more detail the structure of prior art trimmer 10 consideration will first be given to the general manner in which the trimmer is used. A user removes cap 22 (which protects blades 20, 16) from the upper end of outer handle 12. The user then grips surface 24 between the thumb and forefinger of one hand and grips surface 26 between the thumb and forefinger of the other hand. For trimming nose hairs, the upper end of outer handle 12 is inserted approximately 1/8 inch into one of the user's nostrils. Outer handle 12 is held in place while inner handle 14 is rotated back and forth by the user. Such rotation turns inner blade 20 relative to outer blade 16 thereby cutting hairs in a known manner.
Considering now in more detail the structure of prior art trimmer 10, inner blade includes six upright teeth, like teeth 28, 30 in FIG. 3, which are equally spaced about the circumference of inner blade 20. Each tooth has a cutting edge on either side thereof, one of which is cutting edge 32 on tooth 28. The lower end of inner blade 20 includes a generally square opening 34 defined by edges 36, 38, 40, 42 in FIG. 4.
Outer blade 16 includes three upright teeth, two of which are teeth 44, 46, which are equally spaced about the circumference of the outer blade. The third tooth is obscured behind tooth 46 in the view of FIG. 2. Outer blade 16 has a lower end 48, in FIG. 3, which is abutted against an annular lip 50 formed on the radially inner surface of bore 18. Blade 16 is sized to be press fit into bore 18 where it is firmly held in place.
The upper end of outer handle 12 includes six upright prongs, like prongs 51, 53, 55, 57, which are equally spaced about the perimeter of outer handle 12. Bore 18 includes a cylindrical portion 52 which extends downwardly from annular lip 50 and connects to a slightly tapered portion 54. Tapered portion 54 connects to an even more tapered portion 56 of bore 18 which in turn connects with another cylindrical portion 58. An annular groove 60 is formed on the radially inner surface of cylindrical portion 58.
Considering now inner handle 14, an upper cylindrical portion 62 includes an axial cylindrical bore 64 (in FIG. 3) therethrough. A generally square nipple 66 extends upwardly from the top of upper cylindrical portion 62. As can be seen in FIGS. 3 and 4, edges 36-42 fit around nipple 66 and substantially abut against the sides of the nipple. This resists relative rotational movement between inner blade 20 and inner handle 14. A lower cylindrical portion 66 on inner handle 14 includes a ridge 68 formed on a radially outer surface thereof.
A generally cylindrical metal insert 69 is press fit into a lower end of inner handle 14 and includes a cylindrical lower end 71 which abuts against the lowermost surface of inner handle 14. Metal insert 69 adds weight to the trimmer and thereby improves a user's ability to control the trimmer during a cutting operation.
Finishing now the description of the structure of prior art trimmer 10, a tapered pin 70 includes a head 72 having substantially planar undersurface 74. A shaft 76 includes a generally cylindrical portion which extends downwardly from surface 72 and then a tapered portion, best viewable in FIG. 3, which extends to the lower end of the pin.
Consideration will now be given to the manufacture and assembly of the components of prior art trimmer 10. Outer handle 12 and inner handle 14 are molded from polypropylene in a known manner. Blades 16, 20 are made from nickel alloy, also in a known manner. In assembling the components of the trimmer illustrated in FIG. 2, outer blade 16 is first inserted into outer handle 12 until end 48 is firmly abutted against annular lip 50. Next, inner blade 20 is pinned to inner handle 14 independently of the outer handle and outer blade combination. This is accomplished by first manually inserting pin 70 part way into bore 64. The opening defined by edges 36-42 in inner blade 20 (FIG. 4) is then manually guided over head 72 of the pin and edges 36-42 are positioned adjacent nipple 66 as shown in FIGS. 3 and 4.
Thereafter, the arbor press is used to seat pin 70 into bore 64 as shown in FIG. 3. Pin 70, nipple 66, bore 64 and inner blade 20 are sized so that surface 74 adjacent the perimeter of head 72 firmly abuts the lower end of blade 20. When in this position, the pin is securely press fit into bore 64 and undersurface 74 compresses inner blade 20 against the upper surface of upper cylindrical portion 62.
Inner handle 14, with inner blade 20 mounted thereon as described above, is next manually inserted into outer handle 12 until the upper portion of inner blade 20 is received within the lower portion of outer blade 16. Due to the close clearance between inner blade 20 and outer blade 16, rotation of inner handle 14 relative to outer handle 12 is sometimes required to permit the upper portion of inner blade 20 to be received within the lower portion of outer blade 16. The arbor press is then used to complete the press fit of inner handle 14 into outer handle 12 until ridge 68 pops into groove 60. When the ridge is received in the groove, the trimmer is configured as depicted in FIGS. 1, 3, and 4. Groove 60 and ridge 68 permit relative rotational movement of the handles (and therefore of the inner and outer blades) while resisting relative axial movement of the handles.
The foregoing structure and assembly process is disadvantageous for several reasons. First, when the inner handle is press fit into the outer handle as described above, outer blade 16 is sometimes shoved out of its seat on annular lip 50. Also, teeth on inner blade 20, like teeth 28, 30, are sometimes bent thereby impairing cutting action of the trimmer. Although it is possible to press fit inner handle 14 into outer handle 12 prior to mounting inner blade 20 with pin 70, it would be very difficult if not impossible to thereafter align edges 36-42 of the inner blade with the square sides of nipple
The foregoing assembly process is also disadvantageous because of the numerous press fit operations which are labor intensive.